Since this is web based and moderately trafficked, efficiency and scalability is important to avoid repeatedly SELECTing an ever growing number of records. ... I want to do this the Right Way™, and avoid all unnecessary server load.

dragonchild gave you the right answer from the perspective of having a normalized schema, but didn't discuss performance.

If you have a Group table, indexed by group ID, and a linking table indexed by user ID + group ID, the JOIN you need to get from a user ID to a list of group names will scale fairly well. Because you have indexes, you're not scanning entire tables. Because of the composite index on the linking table, MySQL can do a partial key lookup (which avoids scanning the entire table), and can pull the group ID out of the index. From there, the lookup of the corresponding Group record is done using an index.

If you're skeptical, as you should be if you're concerned about scalability, prototype this scheme and benchmark it.

In reply to Re: MySQL / Perl theory & design conundrum by dws
in thread [untitled node, ID 280779] by Samn

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